Abū ʿAlī al-Ḥasan ibn al-Ḥasan ibn al-Haytha


he was an Arab Philosopher who made HUGE contributions to the world of science, math, etc… but mostly we need to know who he is because he may be the great-great-grandfather of optics.

His most famous work is his seven-volume treatise on optics Kitab al-Manazir (Book of Optics), written from 1011CE to 1021CE. It is SUPER long and crazy complex, but what you should know is his biggest achievement was to come up with a theory which successfully combined parts of the mathematical ray arguments of Euclid, the medical tradition of Galen, and the intromission theories of Aristotle. Alhazen’s intromission theory asserted that “from each point of every colored body, illuminated by any light, issue light and color along every straight line that can be drawn from that point”. This is about 65 years before the Chinese start writing about it.

He described a ‘dark chamber’ and experimented with images seen through the pinhole. He arranged three candles in a row and put a screen with a small hole between the candles and the wall. He noted that images were formed only by means of small holes and that the candle to the right made an image to the left on the wall. I know it seems like a “so what” kind of thing, but it was super important.

AND I just want you to know this name.

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